1. Field of the Invention
The present invention relates to a flux-cored wire for stainless steel arc welding that has an outer metal sheath of stainless steel, and is used for welding of stainless steels, dissimilar welding between stainless steels and carbon steels or low alloy steels, underlaying welding in a side of cladding materials of stainless-clad steel, and underlaying welding when in build-up welding of stainless steel weld metals to carbon steels or low alloy steels. Specifically, it relates to a flux-cored wire for stainless steel arc welding exhibiting outstanding welding workability in welding in such a small current as a welding current of no more than 150A, and simultaneously having excellent re-arc startability.
2. Prior Art
Under recent demand for outstanding welding workability and high welding efficiency, a flux-cored wire electrode having these characteristics has increasingly been used. In particular, flux-cored wire electrodes are frequently used in welding of stainless steels. There have been developed flux-cored wire electrodes having a composition adapted to various kinds of base materials, and flux-cored wire electrodes adapted to various welding postures.
In a field of stainless steel, so-called welding of a thick sheet is very rare, and thin sheet welding is performed in many cases. Especially in welding of sheets having a thickness of no more than 3 mm, wires having a thin diameter, such as of 0.8 mm or 0.9 mm, are commonly used.
JP-A No.63-13695 discloses a flux-cored wire electrode having outstanding welding workability in a field of welding of such a small current region as welding currents of 80 through 150 A. Although this technique adopts a wire having a diameter of 0.8 mm in welding about 2 mm of sheet thickness, it is difficult to apply this technique to a wire having a diameter of 1.2 mm.
Manufacturing flux-cored wire for stainless steel arc welding, as understood from JP-A NO. 56-86699, confronts a situation in which thinner the diameter of wires, more difficult in manufacturing the same, thus requiring such a heat-treatment as annealing during wire drawing processing, suffering from high production and supplying cost as compared with wires having diameters of 1.2 mm or 1.6 mm.
To solve the problems, the present invention aims at providing a flux-cored wire for stainless steel arc welding exhibiting excellent welding workability especially for thin sheet stainless steel.
In one aspect, a flux-cored wire for stainless steel arc welding according to the present invention has flux filled up in an outer metal sheath made of stainless steel, wherein the flux includes, as percentage to total weight of the wire, TiO2: 5.5 through 10.0 mass %, SiO2: 1.5 through 3.0 mass %, Al2O3: 0.5 through 1.5 mass %, and fluorine compound (by a value expressed in terms of fluorine): 0.10 through 0.15 mass %, and wherein the flux has a flux rate of 25 through 45%, and a total amount of slag forming ingredient is 8 through 14 mass % as a percentage in the total weight of the wire. It should be noted here that an amount of ZrO2 is limited to no more than 0.1 mass % as a percentage in the total weight of the wire.
According to the aspect of the present invention, as welding materials for thin sheet stainless steel, the flux-cored wire for stainless steel arc welding is excellent not only in welding workability in a low current region but also in welding workability in a current region usually used. Therefore, the present invention may contribute to wide spread use of the flux-cored wire electrode and also contribute to improvement in workability.
According to another aspect of the present invention, it is effective that the flux-cored wire for stainless steel arc welding is applied to wires having diameters of no less than 1.2 mm.
In still another aspect of the present invention, it is more preferable that the flux rate is set to be 30 through 40%.
In yet another aspect of the present invention, it is more preferable that a total amount of slag forming ingredient included in the flux is set to be 9 through 12 mass % in a total weight of the wire.